Fortified rosin size agent



United States PatefifU 'FORTIFIED ROSIN SIZE AGENT Herbert G. Arlt, Jr., Glenbrook, Conn., assignor to American 'Cyanamid Company, New York, N.Y., a corporation of Maine No Drawing. Filed Oct. 31, 1957, Ser. No. 693,508

'3 Claims. (Cl. 106-238) The present invention relates to a novel sizing agent for paper. More particularly, the invention relates to rosin size fortified by a combined content of acetylenedicarboxylic acid.

Sized paper is customarily manufactured by forming an aqueous suspension of cellulose papermaking fibers, adding an aqueous solution of rosin size thereto, precipitating the size on the fibers by the action of alum, sheeting the fibers to form a web, and drying the web to yield paper. The precipitated size more or less coats the fibers, rendering them resistant to wetting by water.

The discovery has now been made that the paper size consisting essentially of the at least partially neutralized Diels-Alder reaction product of rosin with a small amount of acetylenedicarboxylic acid is substantially more efiective on a weight-for-weight basis in imparting water-resistance to the fibers thanordinary rosin size. I have found that the presence of minor amount of combined acetylenedicarboxylic acid in the size makes a major improvement in the amount of water-resistance imparted.

Evidently then the invention rests on the discovery that rosin. .This discovery was surprising as the reaction of rosin with acetylenedicarboxylic acid does not change the number of double bonds present, and in the past chemically improved rosin sizes have generally had a decreased content of double bonds.

Broadly the sizing agent of the present invention con sists essentially of the Diels-Alder adduct or reaction product of rosin with a small but effective amount of acetylenedicarboxylic acid as agent increasing the Water-resistant properties of the size, neutralized as described below. The fortifying action of the acetylenedicarboxylic acid becomes first apparent when the size contains about 2% (approximately mol) of acetylenedicarboxylic acid based on the free and combined rosin present, and accordingly this is regarded as the minimum practical amount. The fortifying action improves with larger amounts of acid, but beyond 12.5 %15 (approximately /3 mol) the improvement efiected by the acid is slight, and accordingly this is regarded as the upper practical limit. In practice I prefer the size to contain between 3% and 10% of acetylenedicarboxylic acid based on the free and combined rosin present as in this range the improvement in sizing per increment of acetylenedicarboxylic acid is about at the maximum.

The reaction product is neutralized with sufficient alkali metal alkali to render it water dispersible. For this at least about 60% neutralization is necessary. Water dispersibility is much improved when the size is neutralized in the range of 70%90%, and this is accordingly gen erally preferred when the size is to be used without drying. In dry size manufacture, however, We find the drying step and the subsequent reconstitution of the size in water to be easiest when the size is completely neutralized.

According to theory, the reaction of rosin with acetylenedicarboxylic acid proceeds according to the following equation acetylenedicarboxylic acid acts as a fortifyingagent for I i tilc However, the correctness of this theory has not been ascertained in several primary respects. For example, the location of the single bond in the rosin nucleus of. the adduct may be elsewhere than shown. Moreover, some disproportionation may occur resulting in formation of a more complex mixture. Further, in the case of incomjpletely neutralized adducts, it has not been ascertained which carboxyl groups are neutralized. For these reasons the sizing agent of the present invention is most conveniently described in terms of its preparation.

The sizing agent may contain such other materials as are ordinarily present in conventional rosin size including wax size, antioxidants, germicides, anti-crystallizing agents, pigments and dyes.

The sizes of the present invention may be prepared by reaction of one mol of rosin with /20 to mol of acetylenedicarboxylic acid, followed by partial or complete saponification and, if desired, by drying. The resinacetylenedicarboxylic acid reaction proceeds satisfactorily at temperatures between the melting point of rosin up to about 250 C. The reaction may be performed below the melting point of rosin by the use of an inert solvent for the reagents. The reaction proceeds'to substantial fco'nt pletion inthree hours at C. and in about 30 minutes at 200 C. It is within the scope of the invention'to react rosin with up to the theoretical maxi-mum amount of acetylenedicarboxylic acid (one mol, or 38% of the weight of the rosin) thereby forming a master batch of the adduct and, after reaction, to decrease the amount of combined acetylenedicarboxylic acid to below 15% by blending the adduct thus formed with unmodified rosin. Likewise it is within the scope of the invention to react rosin with more than 15 by weight of acetylenedicarboxylic acid followed by saponification, also forming a master batch and then to blend the batch thus prepared with sufficient ordinary (unmodified) rosin size to decrease the amount of combined acetylenedicarboxylic acid within the range specified. As rosins there may be employed any of the ordinary rosins including gum rosin, wood rosin and tall oil rosin as well as disproportionated rosins and rosins which have been heat or otherwise treated to decrease their tendency to oxidize or crystallize. As alkalis there may be used sodium hydroxide, sodium carbonate, or the potassium equivalents.

The sizes of the present invention are hydrophilic. The liquid sizing agents can be diluted with water in all proportions. An eifective proportion of rosin size to water is between 50% and 80% by weight of rosin size. The dry sizes of the invention dissolve readily in water, preferably warm water.

The invention will be more particularly described in the examples which represent preferred embodiments of the invention and are not to be construed as limitations thereon.

Example 1 The following illustrates the preparation of liquid rosin-acetylenedicarboxylic acid adduct size according to the present invention.

In a round-bottomed flask provided with thermometer,

stirrer, nitrogen gas inlet tube and reflux column were placed 302 gm. (1 mol) of tall oil rosin, 34.2 gm. (Va mol or 11.2% on the Weight of the rosin) of acetylenedicarboxylic acid and 100 gm. of benzene. The mixture was refluxed for 3.5hours, at which point the Diels-Alder reaction was substantially complete, and the solvent was stripped oif under vacuum. A part of the adduct thus obtained was converted into a 70% solids, 15% free acid liquid size by saponification with aqueous sodium hydroxide solution.

Example 2 The procedure of Example 1 was repeated using half the amount of acetylenedicarboxylic acid, the strength of the caustic solution being decreased to arrive at the same neutralization value.

Example 3 The sizes of Examples 1 and 2 were tested according to a standard laboratory method wherein 1% of size is added to an aqueous suspension of beaten papermaking fibers (50:50 mixed bleached hardwood: bleached sulfite) followed by 1.5% of alum (solids based on the dry Weight of the fibers), the fibers are sheeted to form paper at about 200 lb. basis weight (25" x 40"/50O ream), and the water resistance imparted by the size is determined from the percent increase in the weight of the sheet following total immersion in water for 15 minutes at room temperature. In this test, low increases in weight indicate superior sizing. The results are shown in comparision with the results attained by use of ordinary rosin size, i.e., size prepared directly from tall oil rosin:

Size 1110 Alum, Absorption Run Percent Added Name Percent Percent Percent Added by Wt. Deer.

1 Rosin (control) 1 1.5 55.3 2 Rosiu5.7% ADA 1 1.5 89.2 29.0 3 Rosin-11.7% ADA.-- 1 1.5 38.9 29.6

- 1 Acetylenedicarboxylic acid.

The results show that size having a minor amount of acetylenedicarboxylic acid effects a major increase in water resistance. 7

Example 4 The following illustrates a method for the preparation of dry size according to the present invention.

A part of the Diels-Alder adduct of Example 1 was converted into neutral liquid size at 70% solids by saponification with aqueous sodium hydroxide solution and dried on a rotary laboratory steam heated drum drier. Brittle flakes of neutral dry size were obtained which dissolved readily in water and which gave substantially improved sizing over the sizing imparted by ordinary dry rosin size.

I claim:

1. Rosin size fortified by a content of the Diels-Alder reaction product of rosin with acetylenedicarboxylic acid, said size being at least neutralized with a sodium alkali, the weight of acetylenedicarboxylic acid in said size being between 2% and 15 of the weight of free and combined rosin present therein.

2. Rosin size fortified by a content of the Diels-Alder reaction product of rosin with acetylenedicarboxylic acid, said size being at least neutralized with a sodium alkali, the weight of acetylenedicarboxylic acid in said size being between 3% and 10% of the weight of free and combined rosin present therein.

3. An aqueous solution containing between 50% and by weight of the rosin size of claim 2.

References Cited in the file of this patent UNITED STATES PATENTS 2,791,578 Drechsel May 7, 1957 OTHER REFERENCES Sandermann: Ber. Deutsch Chem. Gesell., vol. 76 (1943), pages 1257-60.

Surrey: Name Reactions in Organic Chemistry, Academic Press Inc., New York (1954), pages 56-57. 

1. ROSIN SIZE FORTIFIED BY A CONTENT OF THE DIELS-ALDER REACTION PRODUCT OF ROSIN WITH ACETYLENEDICARBOXYLIC ACID, SAID SIZE BEING AT LEAST 60% NEUTRALIZED WITHIN A SODIUM ALKALI, THE WEIGHT OF ACETYLENEDICARBOXYLIC ACID IN SAID SIZE BEING BETWEEN 2% AND 15% OF THE WEIGHT OF FREE AND COMBINED ROSIN PRESENT THEREIN. 